The information presented in this document was created from devices in
a specific lab environment. All of the devices used in this document started
with a cleared (default) configuration. If you are working in a live network,
ensure that you understand the potential impact of any command before using
it.

The first thing that needs to be investigated is why the router is
booting up in ROMmon mode (indicated by the "rommon # >" or ">" prompt).
Determine whether the cause is due to the change of the configuration register
value, or a corrupted Cisco IOS software image.

If the router has a valid Cisco IOS software image, then simply
changing the configuration value register to 0x2102 will recover the router.
The procedure for this is explained below.

There is only one way to install an image on the 2500, 3000, AS5100, or
uBR900 Series Routers if the main Cisco IOS software has been deleted or
corrupted. You must use its boot image.

Since you have already determined that the cause of the router booting
up in ROMmon is not due to the configuration register value, the only option
available for recovery is to re-install or upgrade the Cisco IOS software from
a TFTP server using the built-in boot image (Rx-boot) in ROM.

To get into the Rx-boot mode or boot image, do the
following:

If the rommon prompt is "rommon # >", type:

rommon 1 > confreg 0x2101

You must reset or power cycle the router for the new configuration
to take effect: